USB (universal serial bus) interface allows for plug-and-play function, up to 127 physical devices connection, provision of 5V electrical power and requires only one IRQ. Therefore, USB becomes standard interface for nowadays computer. Moreover, the USB 2.0 can provide high data transfer rate of 480 Mbps and is feasible for higher-performance peripheral such as scanners, printers and storage devices.
The conventional ways of data transfer between computers rely on cable connected between printer ports of computers or connected between network interfaces cards of computers. However, the data transfer rate is low by above conventional ways and network interfaces card is required for latter approach. As the prevailing of USB interface, it is proposed to use USB interface for data transfer between computers.
The USB interface is functioned with the master/slave architecture. Therefore, the data transfer between a computer and a peripheral can be established only after the computer is recognized to be a host and the peripheral is recognized to be a device.
To provide data transfer between computers through USB interface, a USB bridge 16 is provided between two computers 12 and 18, as shown in FIG. 1. The USB bridge 16 is connected to a host controller 123 of the computer 12 through a USB cable 141, and connected to a host controller 183 of the computer 18 through a USB cable 143. In this scheme, both of the computers 12 and 18 provide host function and the USB bridge 16 provides device function to establish data transfer between the two computers 12 and 18.
In above approach, one USB bridge and two USB cables are required to achieve data transfer between two computers. It costs higher expense and is inconvenient for user.
Moreover, the USB bridge is further modified to incorporate into a USB cable. However, the USB cable with bridging function has higher cost and cannot be used for data transfer between computer and peripheral.